The subject matter of the present disclosure broadly relates to the art of gas spring devices and, more particularly, to gas spring assemblies that are capable of providing internal pressurized gas damping. Suspension systems including one or more of such gas spring assemblies as well as methods of manufacture are also included.
The subject matter of the present disclosure may find particular application and use in conjunction with components for wheeled vehicles, and will be shown and described herein with reference thereto. However, it is to be appreciated that the subject matter of the present disclosure is also amenable to use in other applications and environments, and that the specific uses shown and described herein are merely exemplary. For example, the subject matter of the present disclosure could be used in connection with gas spring assemblies of non-wheeled vehicles, support structures, height adjusting systems and actuators associated with industrial machinery, components thereof and/or other such equipment. Accordingly, the subject matter of the present disclosure is not intended to be limited to use associated with suspension systems of wheeled vehicles.
Wheeled motor vehicles of most types and kinds include a sprung mass, such as a body or chassis, for example, and an unsprung mass, such as two or more axles or other wheel-engaging members, for example, with a suspension system disposed therebetween. Typically, a suspension system will include a plurality of spring devices as well as a plurality of damping devices that together permit the sprung and unsprung masses of the vehicle to move in a somewhat controlled manner relative to one another. Generally, the plurality of spring elements function to accommodate forces and loads associated with the operation and use of the vehicle, and the plurality of damping devices are operative to dissipate undesired inputs and movements of the vehicle, particularly during dynamic operation thereof. Movement of the sprung and unsprung masses toward one another is normally referred to in the art as jounce motion while movement of the sprung and unsprung masses away from one another is commonly referred to in the art as rebound motion.
In many applications involving vehicle suspension systems, it may be desirable to utilize spring elements that have as low of a spring rate as is practical, as the use of lower spring rate elements can provide improved ride quality and comfort compared to spring elements having higher spring rates. That is, it is well understood in the art that the use of spring elements having higher spring rates (i.e., stiffer springs) will transmit a greater magnitude of road inputs into the sprung mass of the vehicle and that this typically results in a rougher, less-comfortable ride. Whereas, the use of spring elements having lower spring rates (i.e., softer, more-compliant springs) will transmit a lesser amount of road inputs into the sprung mass and will, thus, provide a more comfortable ride.
Generally, it is possible to reduce the spring rate of gas springs, thereby improving ride comfort, by increasing the volume of pressurized gas operatively associated with the gas spring. This is commonly done by placing an additional chamber, cavity or volume filled with pressurized gas into fluid communication with the primary spring chamber of the gas spring.
The one or more damping elements can, in some cases, be of a type and kind that utilize gaseous fluid rather than liquid as the working medium. In known constructions, the pressurized gas damping element can permit gas flow between two or more volumes of pressurized gas, such as through one or more orifices or through one or more valve ports. Generally, there is some resistance to the movement of pressurized gas through these passages or ports. This resistance acts to dissipate energy associated with gas springs and/or suspension systems, and thereby provide some measure of damping.
However, various disadvantages exist with known gas spring constructions that include additional gas volumes to assist in reducing the spring rate of the gas spring, and at least some of these disadvantages involve the movement of air between the two volumes. That is, the flow of pressurized gas between the two volumes is at least partially dependent upon the size, length, shape and number of fluid pathways connecting the two volumes. It will be appreciated that one or more, very large, fluid-communication pathways would permit increased quantities of pressurized gas to flow between the two volumes. However, such pathways would provide reduced resistance to gas flow and, thus, provide minimal or at least decreased damping characteristics. What's more, such very large pathways are often difficult to provide, given the limited operating and mounting envelopes normally associated with vehicle suspension systems.
Increased damping performance can, in some cases, be achieved by reducing the size, increasing the length, altering the shape and/or reducing the number of fluid pathways between the two volumes. Such alterations would, however, normally provide increased damping performance at the expense of other performance characteristics of the gas spring assemblies. That is, the changes that increase the resistance to flow through the passages and, thus, increase damping performance will typically also decrease the effectiveness of the additional gas volume in reducing the spring rate of the gas spring.
Notwithstanding the overall success of known constructions, certain disadvantages may still exist that could be limiting to broader adoption and/or use of gas spring devices. Accordingly, it is believed desirable to develop gas spring devices that overcome the foregoing and/or other problems or disadvantages of known designs, and/or otherwise advance the art of gas spring devices.